Conventionally, various apparatuses which calculate a traveling status (moving status) of a movable body have been proposed. For example, JP2008-014721A discloses an attitude calculating apparatus attached to a ship. An attitude calculating apparatus generally calculates an attitude angle of a ship by using positional information of a plurality of antennas disposed at different positions on the ship.
In the attitude calculating apparatus in JP2008-014721A, a plurality of antennas are arranged such that magnitudes and directions of baseline vectors, each connecting the antennas, are different from each other. The attitude calculating apparatus in JP2008-014721A selects two antennas with longest baseline lengths among the plurality of antennas receiving positioning signals, in other words, the plurality of antennas which can perform positioning. The attitude calculating apparatus in JP2008-014721A calculates an attitude angle of the ship based on the obtained positions of the selected two antennas.
As described above, with the conventional attitude calculating apparatus, since the attitude angle is calculated by using the two antennas with the longest baseline lengths as much as possible, the arrangement area for the attitude calculating apparatus on the movable body becomes large. This is for improving the calculation accuracy of the attitude angle since it is generally known that the calculation accuracy of the attitude angle degrades as the baseline becomes shorter.
However, there are cases where the arrangement area for the attitude calculating apparatus on the movable body is limited, and in such cases, a high calculation accuracy of the attitude angle cannot be expected.